Fast paper test detects three diseases at once
- Existing methods for diagnosing Ebola, dengue and yellow fever need laboratories
- The speedy test — based on silver nanoparticles — needs no infrastructure
- It could also help map disease outbreaks if results are uploaded to a database
The device, which looks similar to a commercial pregnancy test and comes with a US$5 price tag, was presented at a conference of the American Chemical Society last week (18 August).
“Using this rapid test, health officials could prioritise further diagnostic and human resources.”
Jennifer Norman, Mercy Corps
The test combines coloured silver nanoparticles with antibodies against each of the three viruses. If a patient has the corresponding virus in their blood, the test pad shows a disease-specific colour within a few minutes.
At the moment, healthcare workers use genetic techniques to examine the DNA in a blood sample and identify a particular virus. This takes several hours and requires a stable laboratory environment.
In contrast, doctors and health workers could use the paper test to detect disease even in remote areas with no power supply or hospital.
However, it is not sensitive enough to replace traditional laboratory tests altogether, and the researchers say that follow-up tests in a clinical environment would be needed to confirm the test’s diagnosis.
Doctors could also help to map the spread of a disease by taking pictures of the test results and uploading them to an online database.
“Because of the GPS and time and day stamp associated with the photo, this map would show where the disease is spreading, or where it is dying out,” says Kimberly Hamad-Schifferli, an associate professor of engineering at MIT.
This could help health authorities to identify and confirm disease outbreaks in rural areas, says Jennifer Norman, director of public health at the UK humanitarian organisation Mercy Corps. “For example, if several patients tested positive for Ebola using this rapid test, health officials could prioritise further diagnostic and human resources for that particular area,” Norman says.
The American Chemical Society presents its cheap test for ebola, dengue and yellow fever.
So far, the device has only been tested using blood samples with added viral proteins rather than actual patient samples. The MIT team is awaiting approval from the US Food and Drug Administration to begin tests in Ebola-affected areas, and hopes that the test can be used widely within a year.
The researchers used 3D printers to manufacture the test themselves, so it is available in only limited quantities for now. The safe disposal of used tests also requires consideration.
“The amount of nanoparticles in a single test is small but the used test may need to be treated as hazardous material,” says Hamad-Schifferli. Mirva Helenius, a Red Cross spokesperson who works in Ebola-stricken Liberia, says the paper test could be useful, but efforts “must continue to focus on what we know works in reducing Ebola cases”. This includes reporting cases in a timely way, tracing patients’ contacts and avoiding practices such as traditional burials that can promote contagion, Helenius says.